Ladle for use in treatment of molten metal



Dec. 3, 1968 w. E. SNOW 3,414,250

LADLE FOR USE IN TREATMENT OF MOLTEN METAL Filed July 51, 1967 2Sheets-Sheet 1 FICS. 1..

y j I I 20 NE? "*{lf INVENTOR WILLIAM E. 5NOW @QZZWmWMW ATTORNEYS Dec.3, 1968 w. E. SNOW 3,414,250

LADLE FOR USE IN TREATMENT OF MOLTEN METAL Filed July 31, 1967 2Sheets-Sheet 2 l 10 G- 09w 15 25 18 WILLIAME.SNOW

ATTORNEYS United States Patent 3,414,250 LADLE FOR USE IN TREATMENT OFMOLTEN METAL William E. Snow, Birmingham, Ala., assignor to AmericanCast Iron Pipe Company, Birmingham, Ala., a corporation of Georgia FiledJuly 31, 1967, Ser. No. 657,146 Claims. (Cl. 26634) ABSTRACT OF THEDISCLOSURE A ladle for use in the treatment of molten metal having arefractory-lined metal shell open at both top and bottom, a separatelyformed bottom closure detachably connected to the shell, and a wall ofrefractory material fixed to and extending transversely across theinterior of the shell at a position adjacent, but spaced above, thebottom end thereof, the space between the wall and the bottom closurebeing adapted to contain a quantity of treating material in lump-likeform, .and the wall having a plurality of vertically extending openingstherein for permitting contact between molten metal in the ladle and thetreating material. The openings in the wall may be formed by ceramictubes having inside diameters less than the minimum lump size of thetreating material so as to prevent the treating material from floatingupwardly to the surface of the molten metal.

Background of the invention This invention relates to ladles for use inconnection with the introduction of low boiling point reactive metalsinto molten baths of other metals for such purposes as degassing, slagreduction, alloying and nodularization, and more particularly to a ladleof improved construction for use in treating molten metal with treatingagents in the form of briquettes, filled metallic skeletons andimpregnated porous refractories.

It is well known that metals selected from Groups 1, La, [II and -IIa ofthe periodic table of elements can be used in the treatment of othermolten metals for the purpose of degassing, desulfurizing, deslagging orcausing the formation of nodular graphite to produce ductile iron. Theseselected reactive metals have been used primarily to treat base metalssuch as copper, steel or cast iron under conditions where thetemperature of the metal to be treated is greater than the boiling pointof the reactive treating metal used.

For example, magnesium, having a boiling point of 2030 F., is commonlyused to treat molten cast iron at temperatures of from 2500 to 2900" F.,while calcium, having a boiling point of 2625 F., may be used to treat molten steel at temperatures of from 2800 to 3200 F. Under suchconditions, the addition to the molten bath of the reactive metal inpure form can result in explosive violence when the reactive metal isconverted to a vapor or gas by the heat of the treated metal.

Prior to the present invention, several methods have been proposed]looking toward the minimization or elimination of the problem ofviolence when treating molten metals with reactive metals of thecharacter ab ove described, such as alloying, powder or mechanicalinjection, briquetting and the use of filled or impregnated metallicskeleton and porous refractory materials. All of these methods, however,have certain disadvantages when carried out in accordance with theteachings of the prior art.

In the alloying method, the reaction is controlled by dilution of thelow boiling point metal with higher boiling point metals which do notproduce a violent reaction. For example, alloys containing magnesium,such as magnesium-ferrosilicon, copper-magnesium and nickel-magicenesium-silicon have been used, the ferrosilicon, copper or nickel havingan extremely high boiling point and acting as a moderator to reduce theviolence of the reaction. Calcium alloys, such ascalcium-manganese-silicon and calcium-silicon, are other examples ofdilution of the reactive metal by alloying with high boiling pointmetals or metalloids. The alloying method, however, requires the paymentof a premium price for the low boiling point metal content in the alloybecause of the special furnaces and procedures required in itsmanufacture.

In the injection method, the reactive metal is forced or blown into themolten metal bath by the use of injection devices of various forms, theviolence being controlled by allowing only a small amount of thereactive metal to come into contact with the molten metal at any onetime. Examples of this method are the injection of magnesium powderusing pressurized nitrogen gas as .a carrier, and the injection ofmagnesium in wire form through a refractory tube. In these procedures,the preparation of magnesium in powder form, or the production of rolledor extruded rods or wires thereof, and the expense involved in the useof a carrier gas and the mechanical equipment required, increasesubstantially the cost of production of the treated metal.

In the briquetting method, mechanical mixtures of powdered reactivemetals, such as magnesium, and powdered carrier materials, such ascarbon or magnesia, are pressure molded into briquettes, either with orwithout incorporation of a binder, and the briquettes are introducedinto a bath of molten metal in one of the conventional ways hereinafterdescribed. Here, again, the cost of the contained percentage of lowboiling point metal is excessive, and difliculty has been experienced inobtaining a slow controlled release of the reactive metal into themolten metal without excessive violence.

Porous sintered iron and Iother porous metallic bodies have had theirpores filled with a reactive metal in molten form, and then, aftersolidification of the latter, have been used as treating agents bysubmersion in a bath of the molten metal to be treated. In this method,the metallic skeleton is intended to slow evolution of the reactivemetal vapor into the molten bath and thereby reduce the degree ofviolence. Bodies of porous metallurgical coke, porous carbon and poriousgraphite having their pores impregnated with a reactive metal are alsoknown to be effective treating agents for molten metals. For example,when magnesium-impregnated coke is submerged in molten iron, themagnesium in the pores of the coke is converted into vapor and entersthe molten iron in a relatively slow, controlled manner due to themoderating effects of the coke.

In the treatment of molten metals with any of the above-describedtreating agents, it is a matter of economic importance to insure maximumutilization (or recovery as it is normally described in the foundryindustry) of the treating agent. The three most commonly used proceduresfor introducing alloys, briquettes, metallic skeletons or porousrefractory materials containing a reactive metal into molten metalare 1) the open ladle method, (2) the sandwich method, and (3) theplunging method.

In the open ladle method, the treating agent is placed on the bottom ofa conventional ladle and the metal to be treated is simply poured intothe ladle on top of the treating agent. This procedure generally resultsin the lowest recovery of the three procedures.

In the sandwich method, a specially designed ladle is provided with apocket or depression in the bottom into which the treating agent isplaced, after which a layer of steel scrap, in the form of punchings orclippings, is placed over the treating agent before the molten metal tobe treated is poured into the ladle. The steel scrap tends to hold thetreating agent on the bottom of the ladle and to form a protective coverto slow down the initial reaction. This method results in betterrecovery of the reactive agent than the open ladle procedure.

In the plunging method, the treating material is placed in an invertedceramic cup or bell which is then plunged into a bath of the moltenmetal to be treated and maintained submerged below the surface thereofuntil the reactive metal has dissipated. This method normally results ina higher degree of recovery than either the open ladle or the sandwichmethod, but the greater recovery or utilization of the reactive metal isoffset to some extent by the high cost of the ceramic plunger and theincreased labor costs of operating and maintaining the latter.

When subjected to contact with molten metal, alloys in lump formcontaining reactive metal in effect dissolve or disintegrate from thesurface of the lumps, the latter becoming smaller and smaller until theydisappear. Properly manufactured briquettes, filled metallic skeletonsand impregnated porous refractories react by expulsion of the reactivemetal in vapor form with little or no change in the outside shape orsize of the carrier during evolution of the metallic vapor, althoughbriquettes normally disintegrate and metallic skeletons dissolve afterthe reaction is complete. However, porous refractory carriers, such asporous coke, carbon or graphite, normally maintain their original shapeand size even after all of the impregnated reactive metal has vaporized.Because of these different characteristics of the respective types oftreating agents, alloys are generally used in the open ladle andsandwich treating methods, while briquettes and impregnated porousrefractory materials are normally used in the plunging method,particularly because, due to their low density and inherent tendency tofloat, briquettes and impregnated porous refractory materials result inextermely low recoveries when used in the open ladle and sandwichmethods.

Although these prior methods have been used in the past with varyingdegrees of satisfaction, a need still exists for an improved method ordevice for more effectively utilizing treating agents in the form ofbriquettes, filled metallic skeletons nad impregnated porousrefractories, which method or device (a) should hold the treating agentas close to the bottom of the treating ladle as practicable so as toinsure a maximum height of molten metal over the treating agent, (b)should disperse the treating agent uniformly over the bottom of theladle so as to minimize violence of the reaction and to increaserecover, (c) should eliminate the use of expensive equipment such asceramic plungers, and (d) should be relatively inexpensive from thestandpoint of both the initial cost of equipment and materials, and thelabor involved in operation and maintenance.

Summary of the invention The present invention resides in a metaltreatment ladle of improved construction which meets the objectives setforth above by providing an otherwise conventional ladle with certainnovel features resulting in increased recovery or utilization of thereactive treating metal, decreased violence of the reaction, decreasedequipment and labor costs, and increased production per hour ofoperation. The greater recovery also results in decreased consumptionand cost of the reactive metal.

In general, the invention comprises a metal treatment ladle wherein therefractory-lined metal shell of the ladle is open at both top andbottom, and is provided with a separately formed, detachable bottomclosure and a wall of refractory material extending transversely acrossthe interior of the shell at a position above the bottom end thereof,the space between the wall and the bottom closure being adapted tocontain a quantity of treating material, and the wall being providedwith a plurality of vertically extending openings therein for permittingcontact between molten metal in the ladle and the treating material.

Brief description of the drawings FIG.1 is a side elevation of one formof metal treatment ladle embodying the invention showing the bottomclosure member detachably connected to the ladle shell;

FIG. 2 is a top plan view of the assembled ladle of FIG. 1;

FIG. 3 is an exploded vertical sectional view of the lower portion ofthe ladle shell and the bottom closure member, showing the elements asthey exist prior to assembly of the ladle, and also showing a quantityof lump-like treating material carried by the closure member; and

FIG. 4 is a vertical section of the lower portion of the assembled ladleready to receive a charge of molten metal to be treated.

Description of the preferred embodiment There is illustrated in theaccompanying drawings a presently preferred form of ladle embodying theinvention which is especially well adapted for treating molten cast ironwith a treating agent of the character disclosed in Patent No.3,321,304, particularly porous coke in lump form having the poresthereof filled with magnesium. Although the following description willtherefore be directed primarily to this specific use of the ladle, itwill be understood that the structure of the present invention is alsousable with various other treating materials in the form of briquettes,or bodies of porous metallic or refractory materials filled orimpregnated with reactive metal.

As shown in the drawings, the ladle comprises a normally vertical steelshell 10 having a refractory lining 11 and trunnions 12, similar toconventional metal treatment ladles except that the shell is open at thebottom as well as at the top, and a separately formed bottom closuremember 13 which is adapted to be detachably connected to the bottom endof the shell by means hereinafter described. The shell 10 may be trulycylindrical or, as shown, may taper slightly from top to bottom, whilethe lining 11 may be formed from either fire bricks, a poured refractoryor a rammed refractory, using conventional materials and techniques.

The shell 10 is also provided with an apertured wall 14 of refractorymaterial which is fixed to and extends transversely across the interiorof the shell at a position adjacent, but spaced above, the bottom end ofthe shell, leaving a space therebeneath sufficient to accommodate asuitable quantity of treating material, such as magnesiumimpregnatedcoke in lump form. In the embodiment illustrated, wall 14 is composed ofa plurality of vertically disposed ceramic tubes 15 disposedsymmetrically, in spaced apart relationship, about the vertical axis ofthe shell (see FIG. 2), the spaces between tubes 15, and between thelatter and the refractory shell lining 11, being filled with arefractory mortar 16 which both holds the tubes in place and binds thewall assembly 14 to the shell lining 11.

The ceramic tubes 15 may conveniently be of the relatively inexpensivetype commonly known as tile down gates, conventionally used as gates andrunners for molten metals in the production of castings in sand molds.The inside diameters of the tubes should be less than the mini: mum lumpsize of the treating agent to be used, While their length should besufficient to insure resistance against breakage when molten iron ispoured into the ladle. 'For example, in a ladle having an iron capacityof approximately 4000 pounds, the Wall 14 may comprise a total of 20tubes each having an inside diameter of 2" and a length of 9", therefractory mortar 16 consisting of a mixture of fireclay, crushed firebricks and water, and the lower ends of the tubes being located 7 /2"from the bottom of the shell 10. In a ladle having an iron capacity of7000 pounds, a total of 35 ceramic tubes 2 /2 in inside diameter and 6"long have been used to form a wall wherein the lower ends of the tubesare located 9 /2" from the bottom of the shell.

The bottom closure member 13 consists of an open topped steel pan havinga vertical cylindrical wall 17 welded to a horizontal bottom plate 18,the Wall 17 having an inside diameter Only slightly greater than theoutside diameter of the bottom end of ladle shell so as to telescopetherewith, and a height of approximately 2" to 4". The bottom plate 18of the closure member has a diameter greater than the outside diameterof wall 17 so as to provide a ledge on which rest the lower ends of aplurality of vertically extending steel ears 19 which are adapted tocooperate with a like number of steel lugs 20 fixed to the outside ofshell 10 adjacent the bottom thereof and steel wedges 21 for detachablyconnecting the closure member to the bottom of the ladle.

Ears 19 project radially outwardly from wall 17 to which the lowerportions of their inner edges are welded, and are provided adjacenttheir upper ends with vertically elongated slots 22 which receive thewedges 21 when the ladle is assembled. Each of lugs 20 consists of twoupwardly converging side plates 23 which are welded to and extendradially outwardly from ladle shell 10, and a vertical end plate 24which is welded to the outer edges of side plates 23 so as to form anupwardly converging guideway for an ear 19. Wedges 21 are formed withflat bottom edges adapted to bear on the flat upper edges of side plates23 of lugs 20, and with inclined, rounded upper edges adapted to bearagainst the correspondingly rounded upper edges of slots 23, the maximumheight of the wedges being greater than the vertical dimension of theslots 23.

Before connecting the bottom closure member 13 and shell 10 to form theassembled ladle shown in FIGS. 1 and 2, a quantity of loose, finelydivided refractory material, such as molding sand, is placed in the panportion of member 13, and is rammed and leveled so as to provide acompacted layer 25 (FIG. 3) of suitable depth and density to seal thebottom end of the shell against the escape or leakage of molten metalwhen the ladle is filled. The sealing material used preferably should bea molding sand of the same type as that normally used in iron and steelfoundries, and should have suflicient clay and water content to providea good green bond. If desired, a thin layer 26 of powdered coke orgraphite dust may be placed on the surface of the sand layer 25 adjacentthe periphery thereof so as to lie between the bottom end of the ladleshell and the sand when the ladle is assembled and to act as a partingagent facilitating detachment of the closure member 13 from the ladleshell 10 after the treatment has been completed.

A predetermined quantity of treating material 27, such asmagnesium-impregnated coke in lump form, is then placed on top of therammed sand layer 25 in the central portion thereof before the ladleshell and the closure member are connected together. In order tomaintain the lumps of treating material in the center of sand layer 25so that they will lie within the space bounded by wall 14 and the lowerend of shell lining 11 when the ladle is assembled, a retaining ring orcollar 28, of a diameter less than the inside diameter of the lower endof lining 11, may be placed on top of the sand layer before the treatingmaterial is placed. Retaining ring 28 may be made of thin sheet metal orany other suitable material which will not adversely alfect thetreatment when it is dissolved by the heat of the molten metal beingtreated.

After the bottom closure member has been thus prepared, as indicated inFIG. 3, the ladle shell is lowered onto the closure member, as by meansof a conventional ladle lifting and transporting bail (not shown)connected to the trunnions 12, while aligning the lugs 20 with the ears19. Wedges 21 are then driven into the slots 22 in cars 19 so as toforce the bottom ends of shell 10 and lining 11 into the peripheralportion of sand layer 25, thereby further compressing that portion ofthe sand, as indicated in FIG. 4, and creating a seal which effectivelypre- 6 vents leakage from the bottom of the assembled ladle when themolten metal to be treated is poured into the ladle.

When the ladle shell and bottom closure member have been assembled andtemporarily locked to one another in the manner described, the lumps oftreating material are effectively trapped in the space between the sandlayer 25 and the bottom of wall 14. A predetermined weight of the moltenmetal to be treated is then poured rapidly into the ladle, some of itpassing downwardly through tubes 15 into the space beneath wall 14 andinto direct contact with the treating material. The treating materialstarts to react immediately, but is prevented from floating to thesurface of the molten metal by the wall 14, due to the fact that thelump size of the material is so selected as to be greater than theinside diameter of tubes 15. As the reactive metal within the treatingmaterial is converted into gas or vapor, it passes upwardly through thetubes and through the molten metal in the ladle with considerably lessviolence than is normally experienced with the open ladle, sandwich andplunging methods of the prior art. During the ladle treatment, a smallamount of gas and steam is produced in the sand layer 25. Consequently,the bottom plate 18 of closure member 13 is provided with a plurality ofvent holes 29 which enable escape of the gas and steam, thus preventingupward passage thereof through the molten metal which would adverselyaffect recovery of the magnesium or other reactive metal in the treatingmaterial.

After the reaction has been completed, the ladle may be skimmed and thenpoured into the desired casting or transferred into another ladle. Afterthe ladle is emptied, the wedges 21 are driven out of the cars 19 so asto detach the closure member 13 from the ladle shell 10, whereupon thespent treating material and sand may be dumped from the member 13 andthe latter prepared for the next treatment. Since the tubes 15 andmortar 16 forming well 14 are refractory materials, the ladle shell maybe used for a number of treatments before replacement of the wall isnecessary.

One of the advantages of the ladle of the present invention notmentioned above is that the treatment can be carried out while the ladleis being transported from one location to another within the foundrywith a consequent saving in time and labor. A further saving inproduction time results from the fact that the same ladle shell can berecycled with a bottom closure member other than the one used for thelast preceding treatment, and which can be charged with sand andtreating material while the ladle shell is in use with the other closuremember.

Although only one specific embodiment of the invention has beendescribed and illustrated in the accompanying drawings, it will beobvious to those skilled in the art that various modifications can bemade in the form, details of construction and arrangement of the partsof the ladle without departing from the inventive concept. For example,it will be evident that means other than the ear, lug and wedgearrangement disclosed may be used for detachably connecting the bottomclosure member to the ladle shell, and that the force required forsealingly assembling the shell and closure member can be provided bymechanical means such as hydraulic rams, instead of by manually wedgingthe elements together. Reference is therefore to behad to the appendedclaims for a definition of the limits of the invention.

I claim:

1. A ladle for use in the treatment of molten metal comprising arefractory-lined metal shell open at both top and bottom, a separatelyformed bottom closure member for said shell, means for detachablyconnecting said closure member to said shell, a wall of refractorymaterial fixed to and extending transversely across the interior of saidshell at a position above the bottom end thereof, the space between saidwall and said closure member being adapted to contain a quantity oftreating material, and a plurality of vertically extending openings insaid wall for permitting contact between molten metal in said shell andsaid treating material.

2. A ladle as claimed in claim 1 including a quantity of compacted,finely divided refractory material in said bottom closure member forsealing the bottom end of said shell against the escape of molten metal.

3. A ladle as claimed in claim 1 wherein said bottom closure member isin the form of an open topped pan having a bottom plate and anupstanding cylindrical wall, the inside diameter of said wall beingslightly greater than the outside diameter of the bottom end of saidshell so as to have a telescopic fit therewith.

4. A ladle as claimed in claim 3 including a quantity of compacted sandin said bottom closure member for sealing the bottom end of said shellagainst the escape of molten metal.

5. A ladle as claimed in claim 1 wherein the means for detachablyconnecting said bottom closure member to said shell comprises aplurality of elongated ears fixed to and extending upwardly from saidclosure member, a like plurality of ear-receiving lugs fixed to saidshell adjacent the bottom end thereof, the upper ends of said earshaving vertically elongated slots therein located above the uppersurfaces of said lugs, and a like plurality of wedges passing throughsaid slots and resting on the upper surfaces of said lugs.

6. A ladle as claimed on claim 1 including a layer of compacted sand insaid bottom closure member for sealing the bottom end of said shellagainst the escape of molten metal, and means for maintaining a quantityof said treating material in position on top of said sand layer withinthe space bounded by said wall of refractory material and the lower endof said shell.

7. A ladle for use in the treatment of molten metal comprising arefractory-lined metal shell open at both top and bottom, a separatelyformed bottom closure member for said shell, means for detachablyconnecting said across the interior of said shell at a position adjacentto, 1

but spaced above, the bottom end thereof, the space between said walland said closure member being adapted to contain a quantity of treatingmaterial in lump form, said wall including a plurality of verticallyextending ceramic tubes for permitting contact between molten metal insaid shell and said treating material.

8. A ladle as claimed in claim 7 wherein the inside diameters of saidtubes are smaller than the minimum dimension of the lumps of treatingmaterial to be used.

9. A ladle as claimed in claim 7 wherein said bottom closure member isin the form of an open topped pan having a bottom plate and anupstanding cylindrical Wall, the inside diameter of said wall beingslightly greater than the outside diameter of the bottom end of saidshell so as to have a telescopic fit therewith, and including a layer ofcompacted sand in said closure member for sealing the bottom end of saidshell against the escape of molten metal.

10. A ladle as claimed in claim 9 including means for maintaining aquantity of said treating material in position on top of said sand layerwithin the space bounded by said wall of refractory material and thelower end of said shell.

References Cited UNITED STATES PATENTS 1,949,051 2/ 1934 Kelly 266-34 X2,323,583 7/1943 Wilson 222-429 X 2,873,188 2/1959 Bieniosek 75-58 X2,918,365 12/1959 Kanamori et al 75-53 X 2,767,084 10/1956 Chandler 7558X ROBERT B. REEVES, Primary Examiner.

N. L. STACK, Assistant Examiner.

